I have a 2x 21in. dell 2005 FPW with a Single Link DVI-D. I have a EVGA GTX 760 SC with Dual Dual Link DVI-D / DVI-I. Can I use A Dual Link DVI-D cable on both.
So in the future i dont have to buy the Dual link after buying a single link.
Dual link cables just have 6 extra pins that single link cables do not. The monitor side will usually not plug up the holes that are not used so you should be able to use a Dual Link cable on it (You will likely be able to use a DVI-I Dual Link cable if it's got empty slots for the analog pins (red in the below image)
Here is another image comparing the different types of connections with the different pin-outs. Most monitors will have a
Both images taken from the Wikipedia page on DVI